Linear actuator with locking means

ABSTRACT

A linear actuator, lock, and release mechanisms for coupling the rod of a power cylinder to an actuatable member subject to secondary forces such as a die or a core of an injection molding machine. The combination includes a piston-cylinder power system incorporating a cross-block movable by a camming force into a locking recess in a power cylinder wall, and a release mechanism utilizing the cross-block to mechanically exert a high breakaway force on the actuatable member upon the initiation of a retraction motion.

United States Patent 1 Jahnke 1 June 5, 1973 [541 LINEAR ACTUATOR WITHLOCKING 3,326,090 6/1967 Cruse ..92 24 MEANS 2,326,138 8/1943 Grant,Jr... .......74/ll0 2,395,223 2/1946 ln res ....74/l10X lnventorl nf lJahnke, Rochester, 2,536,141 1 1951 R ckwell ..74/1 10 1c [73] Assignee:KMS Industries, Inc., Ann Arbor, 'r Emmi' ler Mamn P'Schw?dmn Mich.Assistant Exammer-Abe Hershkovitz Att0rney-Barnes, Kisselle, Raisch &Choate [22] Filed: Apr. 29, 1971 21 Appl. No.: 138,434 [57] ABSTRACT Alinear actuator, lock, and release mechanisms for [52] U 8 Cl 92/2492/27 74/110 coupling the rod of a power cylinder to an actuatable [51]Flsb 15/26 member subject to secondary forces such as a die or a [58]Fie'ld 23 24 27 core of an injection molding machine. The combina- 2 2tion includes a piston-cylinder power system incorporating a cross-blockmovable by a camming force into a locking recess in a power cylinderwall, and a [56] References C'ted release mechanism utilizing thecross-block 10 UNITED STATES PATENTS mechanically exert a high breakawayforce on the actuatable member upon the initiation of a retraction3,429,233 2/1969 Wright ..92 24 motion 3,l50,569 9/1964 Attermeyer..92/28 X 2,811,951 11/1957 Bodem et al. ..92/l4 13 Claims, 8 DrawingFigures PAIENTEDJUH 5 I975 SHEET 1 OF 2 FIG.:L

INVENTOR lV/ZZ/AM .Z' J/IH/VKA" ATTORNEYS LINEAR ACTUATOR WITH LOCKINGMEANS This invention relates to a self-locking actuating arrangement andmore particularly to an arrangement for coupling a driven member to adriving member which moves linearly between a pair of spaced positionswith locking means on the driven member automatically activated to lockthe driven member in one of its positions. Reference is made to a U. S.Pat. to Frank DAscenzo, Jr., No. 3,534,621, issued Oct. 20, 1970,wherein a device for a similar purpose is disclosed.

An object of the present invention is to provide an improved lockingmeans which is compactly arranged within a cylinder.

A further object of the invention is the provision of a locking devicefor a projectible pin, such as a mold core, which incorporates abreakaway mechanism in combination with the locking means to facilitateapplication of sufficient force for breakaway followed by a withdrawalaction.

Another object of the invention is the provision of a device which canbe actuated by fluid pressure when desired and also mechanicallyactuated when necessary.

The present invention eliminates the necessity for a wedge lock actuatorand utilizes a sliding latch mechanism which provides a positive lockingarrangement.

Other objects and features of the invention will be apparent in thefollowing description and claims wherein the principles of operation aresaid further together with the best mode presently contemplated for theinvention.

Drawings accompany the disclosure and the various views thereof may bebriefly described as:

FIG. 1, a sectional view of the assembly showing the relationship of theparts.

FIG. 2, a sectional view on line 22 of FIG. 1.

FIGS. 3 and 4, views of basic parts of FIG. 1 in differing positions.

FIGS. 5, 6, 7, and 8, diagrammatic views illustrating the relationshipof the parts in various positions.

Referring to the drawings:

The assembly shown in FIG. 1 comprises a basic cylinder having a baseflange 12 drilled at 14 to provide a fluid pressure inlet. The bottomend of the cylinder is closed by a threaded plug 16 which has a suitableannular recess 18 and passage 20 to permit pressure to flow from opening14 to an interior chamber 22. Through the plug 16 extends a piston rod24 with suitable sealing relationship and on the top of this piston rodin threaded engagement therewith is a cylindrical shaft 26 having anaxially extending bore 27 therein which is connected to a cross passage28 to the cylinder interior 22.

The shaft 26 has a flange 30 spaced upwardly from its bottom end andbelow this flange, surrounding the shaft, is an annular piston 32 whichis suitably locked to the shaft by one or more keys 34. Above the flange30 is a second piston 42 which in its lower portion is annular in thatit fits around the top portion of the shaft 26. The top of the piston 42has a cylindrical projection 44 which extends out of the cylinder 10through a top end plug 46 having a suitable sealing relation with thecylinder and with the extension 44. An opening 48 at the top of thecylinder serves as a fluid inlet leading through a passage 50 to achamber 52 at the top portion of the cylinder above the piston 42. Itwill be appreciated that the piston 42 has a sliding relationship withthe top portion of the shaft 26.

The shaft 26 has a side recess 54 with a flat chordal base whichaccommodates cross block 56 having a sliding relationship in a recess 58in the top piston 42. The cross block at the left-hand end, as shown inFIG. 1, has an angled surface 60 which terminates in a horizontalsurface 62, these cooperating with a cylindrical plug 64 verticallymounted in piston 42 and having a flat portion 66 bearing against arecessed surface 68 on the cross block (FIG. 2).

On the other side of the cross block 56 there is a 45 angle slot 70shown in FIGS. 3 and 4 cooperating with an angled projection cam 72 onthe chordal base of shaft 26. Recess 68 and surfaces 60, 62 are omittedfrom FIGS. 3 and 4 to allow a clear showing of cam 72 and slot 70. Withthis arrangement, relative vertical movement between the cross block 56and the shaft 26 will cause a shifting of the lock block transversely ofthe shaft (see FIGS. 3 and 4). It will be noted also that internally ofthe cylinder 10 there is a recess 74 which can be annular to receive theend of the cross block 56 when projected as shown in FIG. 1. A fluidpassage 76, shown in dotted lines in FIG. 1, passes through the piston42 connecting recess 52 to recess 22a above the piston 32.

With the device as described, when pressure fluid is injected into thechamber 22 of cylinder 10 through the opening 14, the piston 32 will bedriven upwardly along with the shaft 26. This will carry piston 42upward and cause the projection 44 which, as an example, may be a corepin in a molding system, to be moved upwardly to the position shown inFIGS. 1 and 5. An inner collar on end plug 46 serves as a stop forpiston 42. This upward movement of the shaft 26 causes cam 72 to urgethe cross block 56 to the right so that the cross block, as it reachesthe recess 74 of the cylinder wall, will move into engagement with therecess as viewed in FIGS. 1, 2, 3, and 5. Consequently, any force whichis applied to the projection 44, such as might occur in a die castmolding, is absorbed by the metal-to-metal contact between the crossblock 56 and the cylinder housing so that there is no possibility of aretraction movement of the projection 44.

It will be noted that chamber 22 is connected through passage 28 andaxial bore 27 to a chamber 82 at the top of the shaft 26. This allowsfluid to pass to and from chamber 82.

Assuming that the device is being used in a die casting mold and thecore (projection 44) is ready for retraction, fluid can be introducedthrough the port 48 and passage 50 to the chamber 52 at the top ofcylinder 42. This pressure fluid will flow through the passage 76 inpiston 42 where it will be exposed to the top of the piston 32 causingthe piston to move downwardly relative to the piston 42, pressing theshaft 26 also down wardly. The 45 cam relationship between the crossblock and the shaft will cause the cross block to move to the left asviewed in FIG. 6, thus disengaging the cross block from the cylinderwall. Further movement of the piston 32 causes the lock block to contactthe cam pin 64. The 30 angle of the pin at 65, acting against the 30surface 60 on the cross block, gives a mechanical advantage ofapproximately 2 to 1. When pin 64 is forced upwardly by cam 60, it abutsthe bottom of the collar 80 and serves as a reacting member so thatfurther motion of the cross block will force the piston 42 downward torelease the projection 44 from the core in which it is held (FIG. 7).Further motion of cylinder piston 32 carries the now-released piston 42and the cross block downward through contact of shaft 26 (top ledge 54aof recess 54) with the cross block and effects full release of the corepin 44 from the high shrink material in the mold in which it is held.Additional movement of the cylinder piston 32 will cause the entireassembly to retract as shown in FIG. 8.

It will thus be seen that in the engaged position of the cross block 56,there is a positive relationship which resists any tendency to move thecore pin 44. Secondly, the cross block which does this locking alsoserves to unlock the core projection 44 by reason of the cammingrelationship of the 30 angle surface 60 against the reaction pin 64.Thus, a high degree of force can be applied to break the projection 44loose after which the entire assembly can move downwardly until recycle.

In the initiation of the recycle with the parts as viewed in FIG. 8,pressure below piston 32 will move the piston and the shaft 26 upwardly.Cam 72 on shaft 26 will act in the slot 70 of cross block 56 with acomponent to the right as viewed in the figures and an upward component.Since the movement of cross block 56 to the right is limited by thecylinder wall, the upward component will be effective to lift the crossblock and the piston 42 upwardly until the cross block reaches the lockrecess 74, at which time the end of the cross block will enter therecess and block further movement of the assembly. In this stage, theprojection 44 will be in its operating position.

The piston rod 24 is positioned eccentrically to the piston shaft 26 andthe axial passage 27 to stabilize the moving assembly against rotation.This rod 24 serves as an indicator as to the position of the piston 22.It may be used to actuate an electrical switch if desired.

It will be appreciated that the passage 76 transmits pressure from thetop of piston 42 to the top of piston 32 which adds to the surface forceof the combined pistons. This greater area, together with the two to onemechanical advantage of the 30 angled surfaces 60-65 on pin and crossblock, insures full release of the core pin 44 from the high shrinkmaterial in which it is held.

What is claimed as new is as follows:

1. In a device for shifting a projectable member linearly to a projectedposition and a retracted position, a mechanism to achieve said shiftingand to lock said mechanism in the projected position comprising:

a. a movable body carrying said projectable member,

b. a housing for guiding said body in a lineal path between a firstposition and a second position,

c. a first means in said body movable laterally of said lineal pathbetween a retracted and a projected position to mechanically engage saidhousing in a projected position,

(I. cam means engageable with said first means upon movement of saidfirst means from a projected position to a retracted position to exert ahigh retracting force on said body, and

e. a reaction member movable in said body member in the directions ofsaid lineal path, engageable at one end with a cam surface on said firstmeans and engageable at the other end with a portion of said housing.

2. In a device for shifting a projectable member linearly to a projectedposition and a retracted position,

a mechanism to achieve said shifting and to lock said mechanism in theprojected position comprising:

a. a first piston carrying said projectable member,

b. a cylinder housing with fluid pressure ports at each end having saidfirst piston slidably received therein for guiding said piston in alineal path between a first position and a second position,

c. a first means in said first piston movable laterally of said linealpath between a retracted and a projected position to mechanically engagesaid cylinder housing in a projected position,

d. cam means engageable with said first means upon movement of saidfirst means from a projected position to a retracted position to exert ahigh retracting force on said piston,

e. a second piston axially displaceable relative to said first piston byfluid pressure, and

f. a shaft on said second piston projecting into said first piston, saidshaft carrying said cam means engageable with said first means to shiftit laterally between said projected and retracted positions.

3. A device as defined in claim 2 in which said first means comprises across block slidable in said body having a cam slot on one side toengage a cam surface on said shaft, and a cam surface on an oppositeside to engage said cam means.

4. A device as defined in claim 3 in which said cam means comprises areaction plunger movable in said body in the direction of said linealpath, engageable at one end with said cam surface on said cross blockand at the other end with a portion of said housing.

5. In a device for shifting a projectable member linearly to a projectedposition and a retracted position, a mechanism to achieve said shifting,to releasably lock said projectable member and to exert a high breakawayretracting force on said projectable member comprising, a housingadapted to guide the projectable member in a generally lineal pathbetween projected and retracted positions with respect to said housing,driving means for shifting said projectable member to said projected andretracted positions, a first means movable by said driving means to bearon said housing to retain said projectable member in said projectedposition and to disengage said housing and release said projectablemember, and a second means operably connected with said driving meansand said projectable member, said second means providing a mechanicaladvantage such that the total breakaway retracting force exerted on saidprojectable member is greater than the force produced by said drivingmeans on said projectable member when said projectable member was movedto said projectable position by said driving means at least as saidprojectable member initially moves from said projected position towardsaid retracted position.

6. A device as defined in claim 5 wherein said housing comprises acylinder housing and said driving means comprises a fluid actuatedpiston slidably received in said cylinder housing for generally axialmovement between a first position wherein the projectable member isretracted and a second axially spaced position wherein the projectablemember is extended.

7. A device as defined in claim 6 wherein said second means comprisescam means. I

8. In a device for shifting a projectable member linearly to a projectedposition and a retracted position,

a mechanism to achieve said shifting, to releasably lock saidprojectable member and to exert a high breakaway retracting force onsaid projectable member comprising, a cylinder housing, said housingbeing adapted to guide the projectable member in a generally lineal pathbetween projected and retracted positions with respect to said housing,a fluid actuated first piston slidably received in said cylinder housingfor generally axial movement for shifting said projectable member tosaid projected and retracted positions, a first means movable by saidfirst piston to bear on said housing to retain said projectable memberin said projected position and to disengage said housing and releasesaid projectable member, a second means operably connected with saidfirst piston and said projectable member, said second means providing amechanical advantage greater than unity in exerting a higher breakawayretracting force on said projectable member than the force produced bysaid first piston, said second means exerting said higher breakawayretracting force at least as said projectable member initially movesfrom said projected position toward said retracted position, a movablebody received in said cylinder housing and carrying said projectablemember, and said first means comprises a cross member carried by saidbody and movable laterally of said lineal path of said body to anextended position to bear on said cylinder housing and to a retractedposition to disengage from said cylinder housing.

9. A device as defined in claim 8 in which said second means comprises areaction member movable in said body generally in the direction of saidlineal path thereof, engageable at one end with a cam surface of saidfirst means, and engageable at the other end with a portion of saidcylinder housing.

10. A device as defined in claim 8 in which said body has a passageextending generally linearly therein, and which also comprises anactuator shaft on said first piston and slidably received in saidpassage in said body and cam means on said actuator shaft and said crossmember to effect lateral shifting of said cross member in response torelative movement between said actuator shaft and said body.

11. A device as defined in claim 8 in which said cylinder housing hasfluid pressure ports at each end, said body comprises a second pistonslidable in said cylinder housing and axially displaceable relative tosaid first piston by fluid under pressure, said body has a passageextending therein in the direction of said lineal path thereof, anactuator shaft on said first piston slidably received in said passage,and cam means on said actuator shaft and said cross member to shift saidcross member laterally between retracted and extended positions inresponse to relative movement between said actuator shaft and said body.

12. A device as defined in claim 1 l in which said cam means on saidactuator shaft and said cross member comprises a cam slot on said crossmember to engage a cam surface on said actuator shaft, and said secondmeans comprises a cam surface on said cross member.

13. A device as defined in claim 12 in which said second means alsocomprises a reaction plunger movable in said body in the direction ofsaid lineal path, engageable at one end with said cam surface on saidcross member and at the other end with a portion of said cylinderhousing.

@3 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,736,844 Dated l ne 5, 1973 Inventor(s) William R. Jahnke It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Col. 3, line 62, change "directions" to "directien" Col. 4, lines 19,20, cancei "carrying said cam means engageable" and insert in placethereof "being operably connected" Col. 4, line 24, cancel "on one sideCol. 4, line 25, cancel- "on an opposite side" Col. L line 15, after"said" insert first line 20,

cancel "it" and insert said first means Signed and sealed this 26th dayof February 19711..

(SEAL) I Attest:

EDWARD M.FLETCHER,JR. K g c. MARSHALL DANN Attesting OfficerCommissioner of Patents

1. In a device for shifting a projectable member linearly to a projectedposition and a retracted position, a mechanism to achieve said shiftingand to lock said mechanism in the projected position comprising: a. amovable body carrying said projectable member, b. a housing for guidingsaid body in a lineal path between a first position and a secondposition, c. a first means in said body movable laterally of said linealpath between a retracted and a projected position to mechanically engagesaid housing in a projected position, d. cam means engageable with saidfirst means upon movement of said first means from a projected positionto a retracted position to exert a high retracting force on said body,and e. a reaction member movable in said body member in the directionsof said lineal path, engageable at one end with a cam surface on saidfirst means and engageable at the other end with a portion of saidhousing.
 2. In a device for shifting a projectable member linearly to aprojected position and a retracted position, a mechanism to achieve saidshifting and to lock said mechanism in the projected positioncomprising: a. a first piston carrying said projectable member, b. acylinder housing with fluid pressure ports at each end having said firstpiston slidably received therein for guiding said piston in a linealpath between a first position and a second position, c. a first means insaid first piston movable laterally of said lineal path between aretracted and a projected position to mechanically engage said cylinderhousing in A projected position, d. cam means engageable with said firstmeans upon movement of said first means from a projected position to aretracted position to exert a high retracting force on said piston, e. asecond piston axially displaceable relative to said first piston byfluid pressure, and f. a shaft on said second piston projecting intosaid first piston, said shaft carrying said cam means engageable withsaid first means to shift it laterally between said projected andretracted positions.
 3. A device as defined in claim 2 in which saidfirst means comprises a cross block slidable in said body having a camslot on one side to engage a cam surface on said shaft, and a camsurface on an opposite side to engage said cam means.
 4. A device asdefined in claim 3 in which said cam means comprises a reaction plungermovable in said body in the direction of said lineal path, engageable atone end with said cam surface on said cross block and at the other endwith a portion of said housing.
 5. In a device for shifting aprojectable member linearly to a projected position and a retractedposition, a mechanism to achieve said shifting, to releasably lock saidprojectable member and to exert a high breakaway retracting force onsaid projectable member comprising, a housing adapted to guide theprojectable member in a generally lineal path between projected andretracted positions with respect to said housing, driving means forshifting said projectable member to said projected and retractedpositions, a first means movable by said driving means to bear on saidhousing to retain said projectable member in said projected position andto disengage said housing and release said projectable member, and asecond means operably connected with said driving means and saidprojectable member, said second means providing a mechanical advantagesuch that the total breakaway retracting force exerted on saidprojectable member is greater than the force produced by said drivingmeans on said projectable member when said projectable member was movedto said projectable position by said driving means at least as saidprojectable member initially moves from said projected position towardsaid retracted position.
 6. A device as defined in claim 5 wherein saidhousing comprises a cylinder housing and said driving means comprises afluid actuated piston slidably received in said cylinder housing forgenerally axial movement between a first position wherein theprojectable member is retracted and a second axially spaced positionwherein the projectable member is extended.
 7. A device as defined inclaim 6 wherein said second means comprises cam means.
 8. In a devicefor shifting a projectable member linearly to a projected position and aretracted position, a mechanism to achieve said shifting, to releasablylock said projectable member and to exert a high breakaway retractingforce on said projectable member comprising, a cylinder housing, saidhousing being adapted to guide the projectable member in a generallylineal path between projected and retracted positions with respect tosaid housing, a fluid actuated first piston slidably received in saidcylinder housing for generally axial movement for shifting saidprojectable member to said projected and retracted positions, a firstmeans movable by said first piston to bear on said housing to retainsaid projectable member in said projected position and to disengage saidhousing and release said projectable member, a second means operablyconnected with said first piston and said projectable member, saidsecond means providing a mechanical advantage greater than unity inexerting a higher breakaway retracting force on said projectable memberthan the force produced by said first piston, said second means exertingsaid higher breakaway retracting force at least as said projectablemember initially moves from said projected position toward saidretracted position, a movable body received in said cylinder housing andcarryiNg said projectable member, and said first means comprises a crossmember carried by said body and movable laterally of said lineal path ofsaid body to an extended position to bear on said cylinder housing andto a retracted position to disengage from said cylinder housing.
 9. Adevice as defined in claim 8 in which said second means comprises areaction member movable in said body generally in the direction of saidlineal path thereof, engageable at one end with a cam surface of saidfirst means, and engageable at the other end with a portion of saidcylinder housing.
 10. A device as defined in claim 8 in which said bodyhas a passage extending generally linearly therein, and which alsocomprises an actuator shaft on said first piston and slidably receivedin said passage in said body and cam means on said actuator shaft andsaid cross member to effect lateral shifting of said cross member inresponse to relative movement between said actuator shaft and said body.11. A device as defined in claim 8 in which said cylinder housing hasfluid pressure ports at each end, said body comprises a second pistonslidable in said cylinder housing and axially displaceable relative tosaid first piston by fluid under pressure, said body has a passageextending therein in the direction of said lineal path thereof, anactuator shaft on said first piston slidably received in said passage,and cam means on said actuator shaft and said cross member to shift saidcross member laterally between retracted and extended positions inresponse to relative movement between said actuator shaft and said body.12. A device as defined in claim 11 in which said cam means on saidactuator shaft and said cross member comprises a cam slot on said crossmember to engage a cam surface on said actuator shaft, and said secondmeans comprises a cam surface on said cross member.
 13. A device asdefined in claim 12 in which said second means also comprises a reactionplunger movable in said body in the direction of said lineal path,engageable at one end with said cam surface on said cross member and atthe other end with a portion of said cylinder housing.